Apparatus for orthoptic training purposes



Nov. 11, 1941. LE ROY WOTTRING APPARATUS FOR ORTHOPTIC TRAINING PURPOSES2 Sheets-Shee 1 Filed Nov. 16, 1938 ww V,

INVEJVTOR: Le Roy l Va/frmy.

ATTORNEY Nov; 11, 1941. LE ROY WOTTRING 2,262,217

APPARATUS FOR ORTHOPTIC TRAINING PURPQSES Filed NOV. 16, 1938 2Sheets-Sheet 2 I l1 VVE NTOR.

Le/Poy Waffr/ng.

5 ATTORNIEYZ Patented Nov. 11, 1941 UNITED STATES PATENT OFFICEAPPARATUS FOR ORTHOPTIC TRAINING PURPOSES a corporation of OhioApplication November 16, 1938, Serial No. 240,865

11 Claims.

My invention relates to apparatus for orthoptic training purposes. Ithas to do with apparatus for directing the exercising of the muscles ofthe eyes to improve the tonicity thereof and to correct conditions andhabits of improper innervation. More specifically, it deals with suchapparatus which is particularly useful for the treatment of suppression,suspension, and anomalies of innervation to the extrinsic and intrinsicmuscles.

In my Patent No. 2,091,173 on Apparatus for orthoptic training purposes,which issued August 24, 1937, I described an apparatus for exercisingthe eyes which consisted mainly of a pair of targets adapted to be fusedby the patient and means for moving such targets in a rotary pathwithout overturning and without rocking relative to the line of vision.Also, as disclosed in said patent, I provided a separate light forilluminating each target and I also provided means for flashing eachlight so that each target would be alternately illuminated and withoutillumination during selected periods. The means for flashing the lightsused for illuminating the target was particularly useful in thetreatment of suppression and suspension and for stimulation ofaccommodation.

When using the instrument disclosed in said patent in treating cases ofamblyopia or suppression, the flashing is used to stimulate thesuppressing or suspending eye and to correct anomalies of accommodation.Although the instrument disclosed in my prior patent has many advantagesand has been widely adopted for orthoptic training purposes, I havediscoveredthatit is desirable to provide an improved arrangement forilluminating the targets and for stimulating vision. I have discoveredthat it is desirable to have the eyes light-adapted at all times and tostimulate or inhibit accommodation While still maintaininglight-adaptation rather than to interrupt illumination of the targets inthe manner disclosed in said patent and thereby destroylight-adaptation.

The main object of my invention is to provide an apparatus for orthopictraining purposes which is of such a nature that vision is stimulated bythe use of illuminated targets upon which the eyes iiXate, the apparatusbeing of such a nature that the eyes may be kept light-adaptedconstantly.

The apparatus which I use is in the main of a structure practicallyidentical to that disclosed in my prior Patent No. 2,091,173. However, Iprovide a different and improved arrangement of the targets and themeans for illuminating the targets, for stimulating or inhibitingaccommodation. This arrangement is such that accommodation is stimulatedor inhibited by changing fixation from secondary to primary targets, theprimary and secondary targets being illuminated alternately andtherebykeeping the eyes lightadapted constantly.

Various other objects and advantages will be apparent from the followingdescription.

The apparatus which I preferably use is illustrated in the accompanyingdrawings wherein similar characters of reference designate correspondingparts and wherein:

Figure l is a perspective view of an orthoptic training instrument madein accordance with the principles of my invention.

Figure 2 is a longitudinal section taken through one of the tubes thatis movably mounted on the instrument and carries the primary andsecondary targets, target-illuminating means and associated elements.

Figure 3 is a side elevation of the instrument shown in Figure 1.

Figure 4 is a detail in perspective illustrating the outer end of one ofthe tubes and showing how the eye movements may be observed by thepractitioner.

Figure 5 is a view showing the shape of the targets which I preferablyemploy.

Figure 6 is a diagrammatic illustration of the electrical circuitsemployed in connection with the instrument.

Figure 7 is a side elevation of a tube of the type shown on theinstrument in Figure 1 but provided with additional means whereby theeye movements of the patient may be observed.

With reference to the drawings and particularly to Figures 1 and 3 Ihave illustrated an instrument which, with the exception of the targetarrangement and target-illuminating means, is practically identical withthe instrument disclosed in my Patent No. 2,091,173.

As described in my said patent, the instrument comprises a base I whichis of the construction shown and which carries a casing or housing 4.The housing 4 carries the operating mechanism of the machine which ispractically identical with that described in my prior patent and whichtherefore need not be described herein. At the front and outside of thehousing 4 a stage 20 is mounted in such a manner that it may be moved ina rotary path about a center, as described in said patent. This rotarypath may be varied and the speed of the rotary movement may be asuitable image formed thereon.

positively controlled. Also, themovement of the stage is automaticallyreversed at intervals. All of the mechanism for accomplishing thesedifferent operations is disclosed in detail in my said prior patent.

In the instrument disclosed in my prior patent, the targets to be viewedby the patient were mounted directly on the stage 20, base-out prismswere supported on a supporting arm I! carried bythe base I, and a septumwas provided to insure that each eye would view one target only.However, in the instrument disclosed in this present application thetargets are arranged and supported in a difierent manner and the septumis not employed. Instead two separate tubes 32 are employed which aremounted in the manner illustrated in the drawings. The inner end of eachtube is supported on the stage 2!] while the outer end of each tube issupported on the supporting arm I I.

Each tube 32 has a base-out prism lens I9 secured in its forward'end. Ata point directly behind the lens I9, the tube 32 is provided with anupwardly projecting tubular socket member I50. This socket member I5!)is open at both its upper and lower ends and its lower end communicateswith. the interior of the tube 32. Directly below this socket I50 anddirectly behind the lens I9 is supported a transparent member Illa. Thismember. I9a is supported at an angle of approximately 45 degreesrelative to the axis of the tube .32. In front of the lens I9 a socketI92) is provided for receiving auxiliary plus or minus spherical lenseswhich may be needed for some patients.

The socket I50 is adapted to receive a removable secondary targetreceiving member I5 II which is of tubular form and has a reduced lowerportion that fits intothe socket. The upper enlarged portion of memberI5] is provided with a horizontally disposed substantially semi-circularslot I52 adapted to receive a secondary target 24a. This target 24a ismade of translucent material having a suitable image formed therein andis preferably of the shape illustrated in Fig- 'ure 5. It comprises asemicircular lower portion 24b and an upper substantially rectangularportion 240 with a shoulder Md being formed to limit inward movement ofthe target when inserted in the slot I52. The portion 241) has the sameradius as the interior of the upper portion of. member I5l. The portion280 will project outwardly from member I5l. By gripping portion 240 withthe fingers the portion Mb may be rotated relative to the axis of themember I5I.

'32 a plurality of substantially semicircular slots 155 are formedtherein at longitudinally spaced intervals. Any one of these slots isadapted to receive a primary target 24s. The target 246 is preferablymade of translucent material and has sameshape as target 24a but islarger. The target will be maintained in vertical position after tube 32and is preferably of the same curvature 1 It is of the as the tube. Itmay be rocked relative to the axis of the tube 32 in the same mannerdescribed with reference to target 2 3a. It will be apparent that thedistance of the primary target from the lens I9 may be varied bypositioning the target in different slots. This variation of thepositions of the target will be equivalent to using plus and minusauxiliary lenses in association with the lens I9. A calibrated scaleI55a may be provided adjacent the slots I55 which may be calibrated inquarter diopters to indicate the position of the target.

The rear end of each tube 32 is provided with a light housing I53. Thishousing has a light socket 39 secured to the side thereof which receivesa removable light bulb 33. The bulb 33 is horizontally disposed. Therear end, the sides, the top and the bottom of the housing I55 areclosed. The forward end thereof is open and communicates with the tube32. In front of the bulb 38 in the housing 56 a plurality of sockets I57are provided for receiving one or more square color filters I53. A lightshield I59 pivoted to the top of housing I56 will normally cover thefilter-receiving sockets I57. This color filter may be provided for apurpose which will be explained hereinafter. It will be apparent thatlight from the bulb 38 will illuminate the target 246 in the mannerillustrated in Figure 2. If the filter I53 is in the position indicated,this light will first pass through the filter.

Each of the tubes 32 has its forward end universally connected to thesupporting arm I! and its rear end universally connected to the stage29. For connecting theforward end of each tube to the arm I! a bracket33 is provided. The forward end of the tube is pivotally connected tothe upper end of bracket 33 as at 34. The lower portion of the bracket33 is provided with a pin which fits into a socket i'la provided on theupper end of the arm I! and the pin is free to rotate in the socket. Thepin may be merely slipped into or out of the socket in order to mountthe forward end of the tube 32 on the support IT or to remove ittherefrom. Thus, it will be apparent that the forward end of the tube 32is connected to the support I! in such a manner that it may moveuniversally relative thereto.

The rear end of the tube 32 is universally connected to the stage 29 bythe structure which I will now describe. The connection is made to amember 24 which is vertically adjustable on a plate member or strip 23carried by the stage 20. The member 23 is mounted on the stage inexactly the same manner as the corresponding member disclosed in myprior patent. Also, the member 24 is mounted on the strip 23 inpractically the same manner as the card-holding member 24 of my patent.Movement of the members 23 towards and away from each other iscontrolled by means of the knob 29, as described in my patent.

Each member 23 carries a forwardly projecting lug 23a. The upper portionof a screw 25 is threaded through this lug. The lower portion of thescrew is threaded through a forwardly projecting arm 35a which has itsrear end secured to the lower portion of member 24. By rotating thescrew 25, the member 24 and the arm 35a carried thereby may be adjustedvertically relative to member 23. A calibrated scale 24 is provided onmember 23 to indicate the vertical position of member 24 on member 23.The forward portion of member 35a has a slide 3519 of semicircularcross-section formed thereon.

This slide is adapted to receive a ball portion 31b formed on the lowerend of a pin 31a depending from the rear end of tube 32 to which it issecured. When the stage 20 is rotated, the ball 31b will turn in slide35b and will move longitudinally thereof.

Thus, it will be apparent that the two tubes 32 have their rear endsuniversally connected to the stage 20 and their forward ends universallyconnected to the support II. The forward ends of the two tubes willalways lie close to each other. However, the distance between the rearends of the two tubes may be varied by adjusting the knob 29.Furthermore, the vertical position of the rear end of each of the tubesmay be varied by adjusting the position of the member 24 on the member23. The stage may move in a rotary path and thereby carry the rear endsof the members 32 in a rotary path. Obviously, this will cause theprimary targets 24e carried by the members 32 to move simultaneously inthe same direction and to the same extent through closed paths and thetargets will be prevented from rocking relative to the line of sight andfrom overturning. The universal connections will permit such movement ofthe members 32. During this movement the patient may be viewing thetargets through the lenses I9. In order to prevent all of the weight ofeach member 32 being applied to the stage 20, a counterbalance spring34a is associated with the pivot point 34. This spring is so arrangedthat it will tend to swing the rear end of member 32 upwardly so as torelieve the stage 20 of part of the weight thereof.

Light shields I68 may be associated with the forward ends of tubes 32 toprevent light from outside sources from entering tubes 32 in anyappreciable amounts. A brow rest I6I may also be associated with theforward end of tubes 32. In using this device a single primary target24a is mounted in the rear end of each of the tubes 32. As previouslystated, this is done by placing one of the targets 24c in one of theslots I55. The patient is seated before the instrument and will View thetargets through the lenses I9. When the lights 38 are on, the primarytargets will be illuminated and the patient looking through the tubes 32will see these targets. The patient can fuse these targets when the rearends of the members 32 are adjusted to the proper :1

vertical position by moving the members 24 vertically on the members 23and when the rear ends of the members 32 have been adjusted the properdistance apart by means of the knob 29.

Then if the motor of the machine is started, the

stage will move in a rotary path and the primary targets willconsequently be carried in a rotary path. In the main, the treatment ofthe patient with this instrument may be carried out in substantially thesame way as described in my prior patent by merely using the primarytargets alone.

With this instrument, however, I have provided a different arrangementfor stimulatin or inhibiting accommodations by changing fixation fromthe primary targets 24a to secondary tarfilters I 58a and the imagesthereof will be reflected by the lens I9a forwardly through the lensesI9 into the eyes of the patient. The lights 38 when on will be reflectedthrough the targets 24c, causing the images thereof to be reflectedthrough lenses I9a, lenses I9 into the eyes of the patient. The interiorof tube 32 and of the lower portion of member I5I preferably is providedwith a dull finish I62.

In the overcoming of any anomalies of convergence or accommodation it isvery desirable to keep the eyes of the patient light-adapted at alltimes. However, it is desirable also to stimulate orinhibitaccommodation and convergence by changing fixation from one setof targets to another.

To do this, I control the lights I54 and 38 in such a manner that duringa short period the lights 38 will be on, illuminating the primarytargets 246 so that they can be seen by the patient, and the lights I54will be off so that secondary targets 24a will not be seen. During thenext period, the lights I54 will be on so that secondary targets 24a canbe seen by the patient and the lights 38 will be off so that the primarytargets cannot be seen by the patient. Thus, even when fixation of theeyes on the targets is changed from the primary to the secondary targetsand vice versa, the eyes are kept lightadapted.

With this arrangement both monocular and binocular accomodativeexercises may be carried out. Monocular exercises may be carried out byhaving one of the primary targets illuminated while the other is not andone of the secondary targets illuminated while the other is not, theillumination periods of theprimary and secondary targets alternating.Binocular exercises may be carried out by having both primary targetsilluminated while both secondary targets are dark, and vice versa,the'periods alternating at intervals. The instrument is preferablyconstructed so that the secondary target position is 2.50 diopterscloser to the lens I9 than the primary target position which is atinfinity provided the primary target is at the zero position on scaleI55a. Thus a change in fixation from the primary target to the secondarytarget demands 2.50 diopters of accommodation and no change inconvergence. By inserting auxiliary lenses in the sockets I91) andadjusting the rear ends of tubes 32 to change the convergence angle,almost any adductive and accommodative demand can be instituted, eitherin ratio or in any amount, either function in advance of the other. Theprinciple of this training is the rapid change in binocular focusrequirement from stimulation to inhibition, with the convergence anglefixed,

by alternating fixation from infinity to a near point.

The transparent member I9a is preferably in the form of a base-downprism to eliminate the phantom image from secondary target 24a whichwould otherwise be caused by the double reflection from oppositesurfaces of member Illa into the eye of the patient causing him to seetwo images.

In theseexercises, it is desirable to use color filters in order toobtain a monochromatic light. It is preferable that the color filtersI53a in as-. sociation with the secondary targets be of a stimulatingcolor to obtain a stimulating effect. It is preferable that the colorfilters I58 in association with the primary targets be of .an inhibitorycolor to obtain a sedative effect.

I provide 'means for controlling and flashing the lights I54 and 38.This means isof such a nature that it may be set to turn on lights 38and simultaneously turn oiT lights I 54 and vice v-ersa at intervals.The periods the lights 38 and I54 are on and olT may be adjustedrelative to each other as desired. Furthermore, the light I54 and thelight 33 for either tube may be flashed independently of the lights fortheother tube. Also, one of the lights 38 may be on with thecorresponding light I54 simultaneously off while the other light 38 isoff with the corresponding light I54 simultaneously on, and vice versa.The intensity of the lights for either eye may be controlledindependently of the intensity of those for the other eye. Theillumination for one eye may be completely interrupted without affectingthe illumination of the other eye. The light for one of the targets 246may be flashed while the light for the other target 24c may be constant.Various other illuminating combinations may be obtained with myinstrument for various purposes.

Inv Figure 6, I illustrate a circuit which may be used for controllingthe operation of the lights 33 and the lights. I54 and other parts of myinstrument. Portions of this circuit are the same as the circuitdisclosed in my prior patent and need not be described in detail.

The circuit comprises wires I25 and I25a leading from a sourceofcurrent. Wire I25 is connected to a-motor 42 of a type disclosed in myprior patent. This motor 42 drives the mechanism disposed within housing4 as described in my patent. A switch MI is interposed in the line I25for making and breaking the circuit to motor 42. The line I25a leads to.a master switch I33a. The switch I38a is also connected to a line I35. Aline I39 leads from line I35 and is connected to a jumper plate I40which is also connected to a line I42. When alternating current isemployed, the jumper plate I40 is used but when direct current isemployed this plate is removed. The line I42 is also connected to themotor reversing switch 80. A resistance element I3! is interposed inline I39. A line I36 leads from plate I40 to line I35 to which it isconnected.

The line I35 leads'to one of the double pole double throw switches Maand is connected to a pole 129a thereof. Two of these switches 4Ia areprovided and are identical with each other. One switch is forcontrolling the lights of one of the tubes 32 and the other switch isfor controlling the lights for the other tube 32. The pole I23a of theleft-hand switch is connected by a line I32 to the pole I29a of theother switch. Each of the switches is provided with a dead pole I30a.Furthermore, each of the'switches is provided with poles I29 and I30.Movable contact members I3I and I3Ia are also provided on each switch.The members I3I and I3Ia are adapted to be moved simultaneously bysuitable means. The members I3I and I3Ia are adapted to be .in contactwith poles I33a and I29a, respectively, or with poles I30 and I29,respectively. The poles I30 of the switches 4Ia. are connected by a lineI2'Ia to the lights I54 in series and the line I2Ia. is

also connected to line I251) at a point between lights I54. This lineI25b is also connected to line I21 at a point between lights 38. Thisline I2! connects lights 38 in series and is connected to rheostatswitches 40a which are employed for controlling the intensity ofillumination of the lights for each tube 32. The left-hand rheostatswitch 40a is connected to the contact member I3Ia of the left-handswitch 4Ia by a line I33a. The right-hand rheostat switch 40a isconnected to the contact member 'I3Ia of the right-hand switch 4Ia by aline I331). The line I331) is connected to a pole I 330 of a three poledouble throw switch indicated by numeral 4Ib which includes the movablecontact member I33d. The line I33a is connected to the pole I33e ofswitch M?) which also includes the movable contact member I33f. Thecontact member I33d is connected by line I33g to the movable contact I3Iof the left-hand switch Ma. The pole I3I of the right-hand switch 4Ia isconnected by line I33h with the movable contact I331. The pole I29 ofthe right-hand switch M11 is connected by line I 331 to the movable contactmember I33Ic of switch Mb. The pole I29 of the left-hand switch 4|is connected by line I331 to a line I34. Additional poles I33m, I33n,and I330, are associated with the movable controls I33d, I33k, and 133respectively of switch 4Ia. Means is associated with switch Mb formoving all of the movable contact arms I33d, I337c and I33simultaneously. The line I34 has its upper end connected to pole I33m.Poles I33n and I330 are connected to each other by line-I33p which isalso connected to line I34a. The line I34a has its upper end connectedto pole I33q which is also associated with movable contact member I33Ic.The line I34 has its lower end connected to a contact 500 of a flasherswitch 50b. The line I34a has its lower end connected to the othercontact 500 of flasher switch 5021. A pivoted lever 49b carries acontact 59d on its lower end which is adapted to alternately engage thecontacts 500. This lever is moved about its pivot point at properintervals by means of a cam 49a. This cam may be carried on a shaft 41bwhich is driven by motor 42 in a suitable manner. The cam 49a ispreferably made of two flat members of different contour which may beadjusted relative to each other to vary the intervals at which lever49?) is swung about its pivots. This cam is preferably of such a naturethat a slow flashing of the lights will be obtained and, as previouslystated, the speed of flashing can be varied. The line I34a also isconnected by line I342) to a contact arm 50a of a flasher switch 50. Theline I34 is connected by a line I340 to a contact arm 50a of the otherflasher switch 50. The other arms 50a of the flasher switches areconnected together and to the line I35 by a line I35a. A single poledouble throw switch I3b is provided for selectively connecting line I35to line [35a or line I35 to line I351). The line I 35b is connected tocontact arm 50d carried by lever 49b. The contacts 50a of switches 50are normally spaced apart but are alternately engaged by a cam 49mounted on a shaft 41 (corresponding'to shaft 4'! of my prior patent)which is driven by the motor 42.

With this circuit and cooperating parts the following results can beobtained:

Master switch I38a may be opened or closed to deenergize or energize theentire circuit.

Motor switch I4I may be opened or closed to deenergize or energize themotor circuit independently of the rest of the circuit. 7

Motor reversing switch will be operated by means described in my priorpatent to reverse the motor at intervals.

Rheostat switch 400 at the left may be operated independently to controlthe intensity of illumination for the left eye.

Rheostat switch 40a at the right may be operated independently tocontrol the intensity of illumination for the right eye.

Switch 4Ia at the left may be operated independently so that contactmembers I3I and I3Ia will contact with poles I30a and I29a,respectively. for obtaining constant illumination of light 38 for theleft eye or so that they will contact with poles I30 and I29,respectively, for obtaining alternate flashing of light 38 and light I54for the left eye.

Switch 4Ia at the right may be operated independently so that contactmembers I3I and I3Ia will contact with poles I30a and I29a,respectively, for obtaining constant illumination of light 33 for theright eye or so that they will contact with the poles I30 and I29,respectively, for obtaining alternate flashing of light 38 and light I54for the right eye.

Switch I3b may be operated to selectively connect, flasher switches 50into the circuit for lights 38 and I54 to obtain fast alternate flashesof lights 38 and I54 or to selectively connect flasher switch 50b intothe circuit for lights 38 and I54 to obtain slow alternate flashing ofthese lights. When switch 50b controls the flashing, the on or offperiods may be varied by adjustment of cam 49a. When switches 50 or 50?)control the flashing, the speed of flashing may be varied by varying thespeed of motor 42 by the speed control described in my prior patent.

Switch IIa may be operated to move contact arms I33d, I33lc and I33 tothe right into contact with poles I330, I33q and I332, respectively, toproduce an alternate flashing, that is with the lights 38 and I54 forone eye flashing alternately with the lights 38 and I54 for the othereye or to move contact arms I33d, I33lc and I33 to the left into contactwith poles I33m, I33n and I330, respectively, to cause lights 38 forboth eyes to flash on and oif simultaneously and lights I54 for botheyes to flash on and off simultane ously. However, in both positions ofswitch 4Ia, when the light 38 for one eye is on the light I54 for thateye is off and, vice versa.

Thus, it will be apparent that with this instrument I provide means forchanging fixation from primary to secondary targets, While keeping theeyes constantly light-adapted. I have found that this arrangement isvery desirable for stimulating or inhibiting accommodation.

Although I have specified that secondary targets are provided in thetarget-carrying members II, the instrument can be used without suchsecondary targets. When used in this manher the bulbs I54 will serve asa source of light for keeping the eyes light-adapted when illuminationof the primary targets has been interrupted.

Although I have stressed that the members I50 are provided for receivingthe secondary target-carrying members I5I and light housings I53, theyserve an additional purpose when the secondary targets are not beingused. As illustrated in Figure 4, the image of the eyeball will bereflected in the angularly disposed lens I9a when the patient is lookinginto the tube 32. This image can be seen by the practitioner when helooks downwardly through the member I50. Thus, these members I50 serveas a means for checking fixation.

With the arrangement illustrated in Figure 4, however, when thepractitioner looks down through the member I50 two images of the eyewill appear in the member I So. The phantom image caused by differentreflections of the light, coming from the eye of the patient, byopposite surfaces of member I9a can be eliminated by the arrangementillustrated in Figure 7. Also, with this arrangement it will not benecessary to remove light housing I53 and secondary target carryingmember I5I to observe fixation of the eye. An additional peep-hole I502)may be provided behind member I50. An additional diagonally disposedtransparent member I9d will be disposed in tube 32 below this peep-hole.This member will be in the form of a base-up prism. The combination ofthe proper basedown prism I and base-up prism I9b will eliminate thephantom image of the eye of the patient which would otherwise appear tothe practitioner.

It will be apparent from the above description that I have providedapparatus for orthoptic training purposes having many advantages many ofwhich have been discussed herein and others of which will be apparentfrom the drawings and the following claims.

Having thus described my invention, what I claim is.

1. An optical instrument of the type described comprising a pair ofelongated hollow members so mounted that a patient may look through theforward ends of such members, a translucent target mounted adjacent therear end of each of said members, a source of light in each of saidmembers behind each target, a separate source of light associated witheach of said members so arranged as to direct light into the memberadjacent its forward end, and means for flashing both of said sources oflight in such a manner that when one is off the other is on, said hollowmembers being substantially horizontally disposed and having theirforward ends mounted in substantially fixed relationship and their rearends mounted for adjustment relative to each other, the rear ends ofsaid members being carried by a member movable in a closed path in asubstantially vertical plane.

2. An optical instrument of the type described comprising a pair ofelongated hollow members so mounted that a patient may look through theforward ends of such members, a translucent target mounted adjacent therear end of each of said members, a source of light in each of saidmembers behind each target, a separate source of light associated witheach of said members so arranged as to direct light into the memberadjacent its forward end, a second translucent target associated withthe latter source of light, and means for flashing both of said sourcesof light in such a manner that when one is off the other is on, saidhollow members being substantially horizontally disposed and havingtheir forward ends mounted in substantially fixed relationship and theirrear ends mounted for adjustment relative to each other, the rear endsof said members being carried by a member movable in a closed path in asubstantially vertical plane.

3. An optical instrument of the type described comprising an elongatedhollow member so mounted that a patient may look through the forward endof such member, a translucent target mounted adjacent the rear end ofsaid member, a source of light behind said target, said member beingprovided with a transversely extending extension, a translucent targetdisposed mounted that a patient may look through the forward end of suchmember, a translucent target mounted adjacent the rear end of saidmember, a source of light behind said target, said member being providedwith a transversely exending extension, a source of light in said ex- 3tension, a transparent member located in said member in line with saidextension for reflecting the light'of the source in said extension fromthe forward end of said member, and means for flashing both of saidsources of light in such a manner that when one is off the other is on.

5. An optical instrument of the type described comprising an elongatedhollow member so mounted that a patient may look through the forward endof such member, a translucent target mounted adjacent the rear end ofsaid memher, a source of light behind said target, said member beingprovided with a transverselyextending extension, a translucent targetdisposed in said extension, a source of light behind said target, atransparent member located in said member in line with said extensionfor reflecting the image of the second target'from the forward end ofsaid member, and means for flashing both of said sources of light insuch a manner that when one is off the other is on, said transparentmember being prismatic toeliminate phantom image of the second target.

6. An optical instrument of the type described comprising a pair ofelongated hollow members so mounted that a patient may look through theouter ends of such members, a translucent target mounted adjacent theinner end of each ofsaid members, a source of light in each of saidmembers behind each target, a separate source of light associated witheach of said members so arranged as to direct light into the member-adjacent its outer end, and means for flashing both of said sources oflight in such a manner that when one is off the other is on, said hollowmembers having their outer ends mounted in substantially fixedrelationship and their inner ends mounted for adjustment relative toeach other, the inner-ends of said members being carried by a membermovable in a closed path in a plane substantially normal to the axes ofsaid members. "7. An optical instrument of the type described comprisinga pair of elongated hollow members so mounted that a patient may lookthrough the outer ends of such members, a translucent target mountedadjacent the inner end of each of said members, a source of light ineach of said members behind each target, a separate source of lightassociated with each of said members so arranged as to direct light intothe member adjacent its outer end, a second translucent targetassociated with the latter source of light, and means for flashing bothof said sources of light in. such a manner that when one is off theother is on, said hollow members having their outer ends'insubstantially. fixed relationship and their inner ends mounted foradjustment relative to each other, theinner endsof said members beingcarried by a member movable "in a closed pathin a plane substantiallynormal to the-axes of said members.

8. An optical instrument of the type-described comprising a pair ofelongated hollow members so mounted that a patient may look through theforward ends of such members, a translucent target mounted adjacent therear end of each of said members, -a source of light in each of saidmembers behind each target, a separate source of light associated witheach of said members so arranged as to direct light into the-memberadjacent its forward'end, and'means for flashing both of said sourcesoflight in such a manner that when one is off the other is on, saidhollow members being substantially horizontally disposed, the rear endsof said members being carried by a member movable in aclosed path in asubstantially vertical plane.

9; An optical instrument-ofthetype described comprising a pair ofelongated hollow members so mounted that a-patient may-look through theouter ends of such members, a'translucent target mounted adjacent therear end of each of said members, -a sourceof'lightin eachof saidmembers'behind each target,a separate source of light associated'witheachof said-members so arranged as to direct light intothe memberadjacent its forward end, a-second translucent target associated withthe lattersource of light, and means for flashing both of said sourcesof light in such a mannerthat when oneis oil the otheris on, said hollowmembers being substantially horizontally disposed, the rear ends of saidmembers being carried by a member movable in a closed path in asubstantially vertical plane.

10. An optical instrument of the typedescribed comprising a pair ofelongated hollow members so mounted that a patient may look through theouterends of such members, a translucent target mounted adjacent theinner end of each of said members, a source of light in each of saidmembers behind each target, a separate source of light associated witheach of. said members so arranged as to direct light into the memberadjacent its outer end, and means for flashing both of said sources oflight in such a manner that when one is off the other is on, said hollowmembers having their outer ends pivotally mounted and having their innerends carried by a member movable in a closed path in a planesubstantially normal to the axes of said members.

11. An optical instrument of the type described comprising a pair ofelongated hollow members so'mounted that a patient may look through theouter ends of such members, a translucent target mounted adjacent theinner end of each of said members, a source of light in each of saidmembers behind each target, a separate source of light associated witheach of said members so arranged as to direct light'into the memberadjacent its outer end, a second translucent target associated with thelatter source of light, and means for flashing both of said sources oflight in such a manner that when one' isofi" the other is on, saidhollow members having their outer ends pivotally'mounted and havingtheir inner ends carried by a member movable in a closed path in a planesubstantially normal to the axes of said members.

LE ROY WOTTRING.

